The present invention relates to a BGA semiconductor device having an insulating film.
Conventional technology involves using an insulating film for a BGA semiconductor device. In particular, a commonly used substrate is a base film in which through-holes are made, wiring is printed on the upper face thereof, the insulating film is set on the printed wiring, and a chip is placed on the upper face of the insulating film to provide for gold-streak bonding between the chip and the wiring. These electronic elements are packaged with a resin. Solder balls are welded to the through-holes at the reverse side of the base film. A BGA semiconductor device is manufactured in this manner.
Unfortunately, when the wiring is printed on the base film and the insulating film is further set on the upper face thereof, an unevenness is formed on the insulating film in conjunction with the printing of the wiring pattern, creating gaps between wires and between the wiring and the insulating film covering the upper face thereof. Air is present in these gaps. If the electronic elements are packaged with the resin under such circumstances, air in the gaps expands whereby portions of the base film are blistered to give height inequality to the lower end faces of a number of solder balls welded to the reverse side of the base film. Using the BGA semiconductor device in such conditions precludes the accurate connection of another terminal to the solder balls located at the reverse side of the BGA semiconductor device and the satisfactory functioning of a semiconductor.
It is an object of the present invention to provide a BGA semiconductor device which overcomes the defects mentioned above.
In order to achieve this object, in one embodiment of the present invention, a BGA semiconductor device comprises an insulating film and a base film having metal through-holes and air purge holes formed between the metal through-holes. Air is purged from gaps between the base film and the insulating film via the air purge holes.
In another embodiment of the present invention, a wiring pattern is printed on the upper face of the base film in which the metal through-holes are made, the insulating film is set on the wiring pattern, a chip is placed on the upper face of the insulating film to provide for gold-streak bonding between the chip and the wiring, and these electronic elements are packaged with a resin, while solder balls are welded to the through-holes at the reverse side of the base film. In accordance with the invention, air purge holes are made between the metal through-holes in the base film so that air staying in recessed portions formed between the insulating film set on the upper face of the wiring pattern and the wiring pattern is purged via the purge holes.
According to the present invention, the purge holes located between through-holes are independently made during the formation of the base film, the wiring pattern is printed on the base film, and the insulating film is further set on the upper face thereof.
In this manner, air purge via the purge holes is carried out such that stagnant air is purged from voids formed between each wire-to-wire recessed portion of the wiring pattern and the insulating film set on the upper face thereof until the voids between the base film and the insulating film are cleared out.
If these electronic elements are molded and packaged with the resin under such circumstances, stagnant air completely disappears in the hardened resin. This eliminates the possibility of expansion of air in the molded resin due to heat during molding or heat generated around the BGA semiconductor device, when used.
Therefore, non-continuity with connection terminals during use of the BGA semiconductor device, due to the non-uniform terminal faces of the solder balls welded to the through-holes in the base film, is prevented.